Romantic relationships, in all of their complexity, are a fundamental component of our lives. And as the poet Rainer Maria Rilke mused, “There is scarcely anything more difficult than to love one another.”

So this Valentine’s Day we’re asking, what makes a good relationship? To that end, Holly Parker, a clinical psychologist and instructor for the course The Psychology of Close Relationships, offers her advice on how to have healthy and loving romantic relationships.

1. See the best

Research on perception and attention shows that we see more of what we look for, so if you’re looking for signs of kindness, that’s more likely to stand out to you. How you think about and interpret your partner’s actions, intentions, and words also affects how you feel and understand a situation with them, which in turn affects how you behave toward them.

Put it into practice: Spend a week looking for anything and everything your partner does “right.” You can even jot down anything you notice for each day if you choose.

2. Have fun

Couples who engage in exciting and enjoyable activities together have greater relationship satisfaction from before to after the shared activity. As several studies have shown, couples who play together stay together.

Put it into practice: Choose an activity with your partner that you’ve never done together before that you would both find engaging and fun, such as taking dancing lessons, staying the night at a new town and exploring it, or indoor skydiving. You can also try something with your partner that he or she enjoys that you’ve never done before.

What else is related to long-term passionate love? Sexual intimacy, shared affection, and happiness in life.

3. Have good sex

Increasing research is pointing to a great sex life as predicting better relationship satisfaction—but not the other way around. One such study published in the Journal of Family Psychologyexamined data from hundreds of couples to determine the relationships among sexual satisfaction, marital quality, and marital instability at midlife.

4. Be grateful for your partner

Studies on appreciation in romantic relationships show that expressing gratitude to your partner predicts an increase in your relationship satisfaction. The gratitude you feel inside also predicts your partner’s level of satisfaction. Feeling appreciated by your partner seems to increase how much you appreciate him or her in return—which positively affects how much you feel committed to the relationship and want to do things to meet your partner’s needs.

Put it into practice: Spend time saying “thank you” and letting your partner know how much you truly value him or her. Also, remember to increase the gratitude you actually feel toward your partner, because this also makes a big difference. Reflect on why you appreciate having your partner in your life or what you would miss most if he or she were not in your life.

5. Have a good relationship with yourself

The relationship you have with yourself is arguably the foundation on which your other relationships are built, and studies are supporting this notion. High self-esteem predicts better relationship satisfaction, and high self-esteem of both partners is an even better predictor of strong relationship satisfaction. Moreover, people with high self-esteem appear to respond more constructively and positively during conflict when they think their partner is committed to the relationship, whereas people with low self-esteem don’t do this even when they believe their partner is committed.

Put it into practice: Like most things, increasing the quality of your relationship can take time. Begin from a place that you can believe. It’s okay if right now you have a hard time believing that you’re a worthwhile person. You don’t have to tell yourself that yet if you don’t believe it. Start by identifying at least one thing you like about yourself or one thing you’re good at doing. Then, look for other things from that starting point. Remember, more of what you look for tends to pop out, so look for not only what your partner does right, but what you do right.